It’s the highest level of public concern with faith’s effect on politics since Pew began asking the question in 1996.

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The rise in Americans’ desire to separate religion and politics — from 44 percent in 2004 to 52 percent today — appears due to a surprising increase in conservative distaste for mingling the institutions — from 30 percent in 2004 to half of conservatives expressing the view today.

Among white evangelicals, 36 percent want religious groups to stay out of politics, a dramatic rise from 16 percent four years ago.

The findings come in the wake of the Saddleback Civil Forum on Saturday, when, in unprecedented fashion, both presidential candidates — Republican John McCain and Democrat Barack Obama — joined popular evangelical leader Rick Warren at his megachurch for their first back-to-back campaign appearance.

But the study, the most authoritative national survey of politics and religion, was conducted prior to event, July 31 to Aug. 10. Conducted on mobile and land line phones, the survey had a large national sample of 2,905 adults, with an overall margin of error of plus or minus 2 percentage points.

In the survey, released Thursday, about half of Americans who view gay marriage and abortion as “very important” voting issues say churches should not be involved in politics. In 2004, only one in four voters who saw gay marriage as a top issue said the same, while a third of those who saw abortion as a top issue agreed.

Overall, 48 percent of Americans believe that social conservatives wield “too much” influence in the GOP.

Yet older adults appeared most irked by the mingling of religion and politics. Only 18 percent of Americans age 65 and older said churches should endorse candidates, while roughly a third of voters under age 50 believed a church support for a candidate was appropriate.

The public is also increasingly split over whether they feel “discomfort” when politicians discuss religion in the sphere of public policy, as both Obama and McCain did at length Saturday.

Yet more Americans — half in fact — still say it does not bother them “when politicians talk about how religious they are.” Forty-six percent said they were offended.

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American religiosity, however, remains no less prevalent. The public appears to continue to support expressions of faith by public figures while feeling increasingly uncomfortable when that faith falls into the sphere of politics.

The public believes that a president should have “strong religious beliefs.” Fully 72 percent say so today, a modest uptick since 2004 — including 85 percent of voters who attend church at least once a week and 66 percent of independent voters. Equally, only 29 percent of the public believes there is “too much” expression of religious faith by political leaders.

At the same time, the public’s perception of Democrats' unfriendliness to people of faith has significantly improved, though the issue persists.